Ferroelectric phase transitions in KNO3 embedded into porous glasses

This paper presents the results of dielectric and dilatometric measurements of porous glasses filled with KNO3 from water solution and from the melt. It was shown that ferroelectric phase transition is observed during the cooling process only in KNO3 nanocrystals introduced into the porous matrix. The phase diagram of transition temperatures versus average values of pore dimensions was obtained. The phenomenological model describing the phase transition and size effects in KNO3 crystals is proposed.